From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7F0AC43460 for ; Thu, 29 Apr 2021 18:04:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9CCC76101E for ; Thu, 29 Apr 2021 18:04:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241073AbhD2SFX (ORCPT ); Thu, 29 Apr 2021 14:05:23 -0400 Received: from elvis.franken.de ([193.175.24.41]:52028 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232572AbhD2SFS (ORCPT ); Thu, 29 Apr 2021 14:05:18 -0400 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1lcB1W-00022Q-00; Thu, 29 Apr 2021 20:04:26 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 5E3DCC0D1B; Thu, 29 Apr 2021 20:04:17 +0200 (CEST) Date: Thu, 29 Apr 2021 20:04:17 +0200 From: Thomas Bogendoerfer To: Huang Pei Cc: Zhou Yanjie , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, paul.burton@mips.com, paul@crapouillou.net, siyanteng@loongson.cn, ira.weiny@intel.com, yangtiezhu@loongson.cn, jun.jiang@ingenic.com, dongsheng.qiu@ingenic.com, aric.pzqi@ingenic.com, rick.tyliu@ingenic.com, sernia.zhou@foxmail.com, sihui.liu@ingenic.com Subject: Re: [PATCH] Revert "MIPS: make userspace mapping young by default". Message-ID: <20210429180417.GA10482@alpha.franken.de> References: <1618562868-91115-1-git-send-email-zhouyanjie@wanyeetech.com> <20210416092003.5754967.19768.9603@loongson.cn> <20210419045610.frhzxskec47s5rmq@ambrosehua-HP-xw6600-Workstation> <13e37741-c1b4-2aae-471e-0790adc8db59@wanyeetech.com> <20210420024818.r6jf243oglb2ywbr@ambrosehua-HP-xw6600-Workstation> <20210423145131.GA11112@alpha.franken.de> <6d307cf6-0ed5-e9f9-ae1e-8f2e28b23311@wanyeetech.com> <20210426131146.bj2r4ha7yy5norxa@ambrosehua-HP-xw6600-Workstation> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210426131146.bj2r4ha7yy5norxa@ambrosehua-HP-xw6600-Workstation> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 26, 2021 at 09:11:47PM +0800, Huang Pei wrote: > [ 40.873779] Cause : 4080800c (ExcCode 03) > [ 40.877775] BadVA : 77e23000 > [ 40.880645] PrId : 00d00100 (Ingenic XBurst) > [ 40.884989] Modules linked in: > [ 40.888034] Process Xsession (pid: 1370, threadinfo=ca5ce8d6, > task=61c8f3ad, tls=77e28690) > > !!! This is my first time debug MIPS32 kernel, I think both threadinfo > and task should be at KSEG0, instead of KSEG2 or USEG don't print pointers with %p they will be garbled for security reasons. see Documentation/core-api/printk-formats.rst "A raw pointer value may be printed with %p which will hash the address before printing." > [ 41.233877] Index: 27 pgmask=4kb va=77e22000 asid=5c > [ 41.233877] [pa=06a17000 c=3 d=0 v=0 g=0] [pa=2017a000 c=0 d=0 v=0 > g=0] > > !!! TLB entry is loading a SWAP entry(C=0, pa=swap) at BADV, the pte_buddy point to a valid > PFN(C=3, pa seem ok), but it is impossible, since line 116 must flush the tlb and > replaced swap entry with new page > > Am I missing something? not sure, if I'm on the right track, but with the _PAGE_VALID bit set in the new pte local_r4k_flush_cache_page() will do if ((mm == current->active_mm) && (pte_val(*ptep) & _PAGE_VALID)) vaddr = NULL; and then vaddr ? r4k_blast_dcache_page(addr) : r4k_blast_dcache_user_page(addr); flush the address directly instead with r4k_blast_dcache_user_page(). But the TLB will be updated after the cache flush (which is correct IMHO). So setting the VALID bit too early destroys the logic of flushing cache aliases. Do you agree ? Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]